The final two verses are the most impenetrable.

It is widely regarded as the most impenetrable of the slave camps.

Iron, stone, the most impenetrable of defenses-all were useless against it.

This is magic at its deepest, its most impenetrable, Harry.

But his was of all minds the most impenetrable, save when he wished otherwise.

To many, such frustrations are the price of negotiating with the world's most impenetrable country.

In particular, the people of the Weald were thought to have the most impenetrable accents.

Even so, Tiger is the most impenetrable Mac system yet, filled with new defenses against the dark arts.

It is thus the most earthbound aspects of life that have become the most impenetrable and rarefied.

But Japan is also one of the world's most impenetrable markets.